Method for preparing diazabicyclo-(2, 2, 2)-octane



United States Patent 1 3,166,558 METHOD FOR PREPARING DIAZABIQYCIB- (2,2,2)-0CTANE Rocco L. Mascioii, Media, Pa., assignor to Air Products 3,166,558 Patented Jan. 10, 1965 reaction products being continuously discharged at the opposite end of the catalytic reactor. If the diluent is liquid at ambient temperature, it may be charged in that form in admixture with the hydroxyethylpiperazine or and Chemicals km a cor oration of Delaware 5 separately. Reaction is carried out at temperatures in the No Drawing. Filed Aiig. 11? 1961, Ser. No. 130,750 range of F., preferably at about 0 2 31 m 1 2 0-253 and at space rates (LHSV) of from about 0.2 to 1.0 based on liquid volumes of the hydroxyethylpiperazine The present invention relates to the preparation of compounds charged per volume of catalyst. While supertriethylene diamine, also known as diazabicyclo-(2,2,2)- 10 atmospheric pressures can be used, these offer no adoctane, and is particularly concerned with improved procvantage over atmospheric or subatmospheric pressure esses for the synthesis of this compoundinincreased yields operation. The diluent gas may be used in quantities from readily available and comparatively inexpensive as high as 10 or more mols/mol of hydroxyethylpiperazine raw materials. compound, preference being had for proportions'in the Diazabicyclo-octane is commercially employed as a range of 3 to 5 mols/mol. catalyst for base-catalyzed reactions, particularly in the Any non-reactive gas, vapor or vaporized liquid which preparation of polyurethane plastics, elastomers and is inert or non-reactive in the operation may be used. foams. While this compound had been reported in the Ammonia is a preferred diluent meeting the requirements literature considerably earlier, the first production thereas well as being cheap and readily available. Other diluof in commercial quantities was achieved only in recent ents that may be used include nitrogen and volatile hyyears by processes involving vapor phase reaction of cerdrocarbons of saturated aliphatic or aromatic types, tain alkylene polyamines over solid acidic catalyst, as which are sufficiently refractory so as .not to be cracked described, for example, in U.S. Patent No. 2,937,176. at the reaction temperature employed; examples of which With increasing demand for the compound, attention are pentane, heptane, benzene, and toluene. v i has been directed to improved methods of production to Both N-hydroxyethylpiperazine and N-N'-bis-hydroxyobtain increased yields of product, and/or lower proethylpiperazine duction costs. 1

Early attempts to obtain diazabicyclo-octane by ring f (I) (H) closure of a beta-substituted N-ethyl piperazine had been unsuccessful or obtained yields of no more than about V R H or one to several percent. After a number of unsuccessful L attempts, Hromatka [Berichte 75B, 1302 (1942)] re- N ported the production of idiazabicyclo-octane in fair E OH yields by carefully controlled heating of N-beta bromo- 4 ethyl piperazine hydrobromide; smaller yields were obmay be available commercially in moderate quantities. tained from the corresponding hydrochloride, while the p The mono compound (I) can be readily prepared by corresponding N-hydroxyethyl compound gave considerknown reaction of piperazine with ethylene oxide. Of ably poorer yields. 7 particular interest here is that the bis compound (II) The conversion of N-monoand N-N'-bis-hydroxyis obtained in attractive yield from diethanolamine by ethylpiperazines to diazabicyclo-octane by catalytic vapor 40 cyclodehydration. In the latter reaction, it is not necesphase reaction over silica-alumina, is reported by Ishiguro sary to isolate the pure N,N-bis-hydroxyethylpiperazine; et a1. [1. Pharm. Soc. Japan, 75, 1370 (1955); abstracted but the total reaction product after removal of the water, in Chem. Abs., 50, 10106, (1956)]. According to US. can be charged to the catalytic reactor for production of Patent No. 2,985,658, acceptable yields of diazabicyclothe diazabicyclo-octane. octane are obtained from N-aminoethylpiperazine over Because of the high concentrations of diazabicycloacidic siliceous cracking catalyst. octane in the reactor efiluent obtained by the process of It has now been found that improved yields f diaza the invention, a major portion ofthe diazabicyclo-octane bicyc1o octane are Obtained from or can be initially recovered as a solid of good purity which hydroxyethylpipemzine or from mixtures f these by s formed when the reactlon product 1s cooled. 'I:h1s solid continuous vapor phase reaction in which such hydroxy 1s essentlall-y a hydrate of diazabicyclo-octane with some ethylpiperazine compound or mixture is passed over adherent moiherhquorsiliceous cracking catalyst together with at least 2 mols EXAMPLE I of a gasiform diluent which is stable and non-reactive under the operating conditions employed. y y y p p was Passed Over activated In the preferred practice of the invention the liquid kaolin Catalyst 3 fixed bed reactor in a number reactant and the gasiform diluent are introduced sepa- Separate runs t h Conditions Shown in Table 1 belowrately into a closed reactor containing a fixed bed of In certain of the runs, as indicated, inert gasiform diluent the heated catalyst in granular or pellet form; vapor was added with the charge'in the proportion specifiedz Table I Run No 1 2 3 4 5 a 7 8 LBS 0. 41 0. 42 0. 4 0. 4 1. 0. 1. 22 1. 12 Temp F. (range) 620-635 645-655 665-675 090-700 700-710 725-735 650-680 685-720 Dilue NHa N H: N H3 NH: 1 B2 N; None None Diluent/charge, mols 4/1 4/1 4/1 4/1 4/1 3. 5/1 Liquid recovery, wt. percent- 90. 5 89 92. 6 91. 3 96. 4 84. 5 93. 3 92.7 Composition of liquid reactor efrluent Diazabieyclo-octane, wt. percent 29. 6 36.6 37. 6 35.1 36. 8 43. 4 19. 9 27. 9 Pipcrazine, wt. percent 2.1 3. 9 7. 7 3. 1 1. 9 2. 4 Yield based on charge:

Diazabicyclo-octane, wt. percent 26. 8 32. 6 34. 8 32. 0 35. 3 36. 7 18. 5 25. 8 W1; percent of theoretical 31 38. 8 40. 5 37. 7 41 42.6 21. 5 30 1 Benzene.

The reported liquid hourly space velocity (LHSV) in the above table is based on the total liquid feed. In Run #5, this space velocity includes the benzene as well as the hydroxyethylpiperazine. It will be seen that at any severity level of operation over the range employed (residence time and temperature), use of the diluent obtains substantial yield improvement, in some instances the yield of diazabicyclo-cctane being almost doubled.

The catalyst used in the above runs was an activated kaolin catalyst produced by the methods described in US. Patent 2,904,520.

Other siliceous cracking catalysts that may be employed under substantially similar conditions include acid-activated bentonite clays and gels of the silica-alumina type, or such siliceous gels containing zirconia or magnesia substituting for all or part of the alumina. The siliceous cracking catalysts are those generally having a surface area of at least 80 m. /g.; the preferred silica-alumina catalystsare those having a surface area of at least 180 m. /g. In general, the higher the activity of the catalyst the lower is the reaction temperature to be employed for best results.

Recovery of the diazabicyclo-octane from the reaction mixture is obtained by fractional distillation to separate a cut in the approximate boiling range of the desired compound (about 165 to 175 C.) which on cooling or redistillation and sublimation separates out crystals of diazabicyclo-octane of acceptable purity. By known techniques further recovery of crystalline product can be obtained from the mother liquor. If desired, recovery of the diaZabicyclo-octane from the reaction efliuent can be obtained by the method set out in aforesaid US. Patent No. 2,937,176. In accordance with the method therein described, a cut rich in diazabicyclo-octane is fractionated from a reaction eflluent and cooled. The cooled fraction is purified by trituration one or more times with a normally liquid low boiling aliphatic hydrocarbon, such as n-pentane. Cooling and filtration thereafter yields a white crystalline solid of high purity diazabicyclo-octane.

' EXAMPLE II By an operation similar to that described in Example I, a charge composed of about 40% N-N'-bis-hydroxyethylpiperazine and 60% N-hydroxyethylpiperazine was passed over activated kaolin catalyst with about 4.5 mols ammonia/mol of charge. The reaction was effected in the temperature range of 665-680 F. and with a liquid hourly space velocity of 0.44. The liquid reactor eflluent (87.8% by weight of charge) contained 46.7% by weight diazabicyclo-octane, which is 41.0% by Weight of charge, equivalent to 64% of the theoretical yield.

EXAMPLE III Diethanolamine was reacted with glacial acetic acid mols/mol) in a stirred vessel for 20 hours at 190- 220 C., with approximately 1 mol of water being discharged as steam. The liquid reactor etfiuent contained 34% of N-N'-bishydroxy-ethylpiperazine based on the initial amine and 39% based on the liquid product. The total liquid reactor efiiuent was passed over activated kaolin catalyst at 670 to 700 F. and at 0.46 LHSV, together EXAMPLE IV Diethanolamine was reacted with acetic acid for an extended time at elevated temperature in a manner similar to Example III with similar evolution of water. The liquid product amounted to 88.5% of the diethanolamine and contained 46% N,N-bis-hydroxyethylpiperazine. The liquid product was admixed with N-hydroxyethylpiperazine to provide the charge for the reaction over kaolin catalyst to produce diazabicyclo-octane. The charge composition was 73.2% of the liquid product containing the N,N'-bis-hydroxyethylpiperazine and 26.8% N- hydroxyethylpiperazine.

Conversion to diazabicyclo-octane was effected over activated kaolin cracking catalyst at a temperature in the range of 680690 F. with an LHSV of 0.4, with diluent ammonia present in a mol ratio of about 8 mols NH /mol of charge. The yield of diazabicyclo-octane was 42% based on the N,N'-bis-hydroxyethylpiperazine, or 19.2% based on the diethanolamine.

Obviously many modifications and variations of the present invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

What is claimed is:

1. The method of preparing diazabicyclo-(2,2,2)-octane which comprises initially reacting diethanolamine under acid condensation conditions to eliminate water and effect ring closure producing a reaction product rich in N-N'-bis-hydroxyethylpiperazine, and passing the total reaction product over silica-alumina cracking catalyst at 500-800 F., together with at least 2 mols NH /mol of charge and fractionating the liquid etfluent to isolate a cut consisting essentially of diazabicyclo-(2,2,2)-octane.

2. The method as defined in claim 1 wherein said acid condensation is effected in the presence of a minor quantity of glacial acetic acid and at a temperature of 370 to 440 F. for 10 to 20 hours, and at a pressure of from 1 to 20 atmospheres.

' References Cited in the file of this patent UNITED STATES PATENTS 2,977,363 Farkas et a1 Mar. 28, 1961 2,977,364 Mascioli Mar. 28, 1961 3,038,904 Godfrey June 12, 1962 3,056,788 Brader Oct. 2, 1962 OTHER REFERENCES Chemical Abstracts, v01. 50, p. 10106 (1956).

Ishiguro et al.: Pharm. Soc. of Japan, vol. 75, pp. 1370 1373 (1955), RSI. P. 45.

Sasaki: Yuki Gosei Kagaku Kyckia Shi, vol. 16, pp. 614-624 (1958). 

1. THE METHOD OF PREPARING DIAZABICYCLO-(2,2,2)-OCTANE WHICH COMPRISES INITIALLY REACTING DIETHANOLAMINE UNDER ACID CONDENSATION CONDITIONS TO ELIMINATE WATER AND EFFECT RING CLOSURE PRODUCING A REACTION PRODUCT RICH IN N-N''-BIS-HYDROXYETHYLPIPERAZINE, AND PASSING THE TOTAL REACTION PRODUCT OVER SILICA-ALUMINA CRACKING CATALYST AT 500-800*F., TOGETHER WITH AT LEAST 2 MOLS NH3/MOL OF CHARGE AND FRACTIONATING THE LIQUID EFFLUENT TO ISOLATE A CUT CONSISTING ESSENTIALLY OF DIAZABICYCLO-(2,2,2)-OCTANE. 